Prognostic implication of SOX2 expression in small intestinal adenocarcinoma

The presence of KRAS mutation enhances the stem cell features of colorectal carcinoma cells containing mutant adenomatous polyposis coli (APC). However, their potential role in small intestinal adenocarcinoma remains elusive. Here, we aimed to investigate the clinical significance of cancer stem cell markers expression in the context of small intestinal adenocarcinoma with the KRAS genotype. SOX2, NANOG, and OCT4 expression were assessed by immunohistochemistry and digital image analysis, and their potential association with KRAS was further examined in 185 Korean patients with small intestinal adenocarcinomas, which were collected from 22 institutions in South Korea. Positive expression of SOX2, NANOG, and OCT4 was detected in 65 (35.1%), 94 (50.8%), and 82 (44.3%) of patients, respectively. Patients with high SOX2 (SOX2+) expression displayed worse overall survival compared to those with low SOX2 (SOX2-) expression (P < 0.001). Patients with SOX2+/mutant KRAS (KRAS(MT)) (11.1 months) had significantly shorter overall survival than those with SOX2-/KRAS(WT) (53.6 months) (P < 0.001). In multivariate analysis, SOX2+, distal location, high pT and pN categories, microsatellite stable, and absence of predisposing diseases were independent prognostic factors for worse overall survival. These results suggest that SOX2 expression has the potential to predict clinical outcomes in patients with small intestinal adenocarcinomas.